1. Field of the Invention
The invention relates to a hydrodynamic machine, in particular a hydrodynamic retarder for producing a braking torque by way of a working fluid. The invention relates in particular to hydrodynamic retarders that are used as wear-free continuous brakes in drive trains, in particular in motor vehicle drive trains, for example in trucks.
2. Description of the Related Art
Retarders can be designed as water retarders which use the cooling water of the vehicle as the working medium, or as oil retarders which use an oil as the working medium. The water retarder is usually integrated or tied into the vehicle cooling circuit. The oil retarder in contrast includes an oil circuit and an oil cooling circuit wherein the oil cooling circuit can be integrated into the vehicle cooling circuit or can respectively be tied to same.
Such a retarder includes two bladed wheels which together form a toroidal working chamber, at least one of which rotates about a rotational axis of the hydrodynamic machine. The working chamber can be filled for a first operating condition—braking—with working medium via at least one provided working medium inlet. During braking, a circulatory flow occurs in the working chamber, whereby the working medium hydrodynamically transfers a braking torque and/or a driving power from the first to the second bladed wheel. For a second operating condition—non-braking operation—the working medium is pumped from the working chamber of the retarder, in order to avoid a torque and/or driving power transfer.
In order to avoid unnecessary losses due to synchronous rotation of the rotor in non-braking operation, retarders are moreover known that can be decoupled from the drive or respectively the gearbox of the vehicle. For this, a disconnect device is used. The disconnect device is positioned or arranged between gearbox and retarder as disclosed for example in DE 10 2011 120 620 A1, and as a rule is allocated to the gearbox. It is necessary, in particular with water retarders, that the working medium region and the region housing the components that must be lubricated, such as the bearings and the disconnect device, are separated from one another. The lubrication occurs in general by way of oil from the gearbox.
The allocation to the gearbox has the disadvantage that the retarder cannot be supplied together with the disconnect device as a tested component and mounted to the gearbox, as a result of which the operational reliability of the retarder can be compromised.
One of the objectives of the invention is to alter the design in such a way that the operational reliability is improved.